I love your analyses, Thud (by the way, is that a reference to the F-105?). I'd reached a lot of the points you had. Trying to reconcile Lucas' writing and editing choices makes for a headache, to be sure. And I dump the Special Editions and Rogue One, as they were made years after the fact, meaning more and more misinterpretations find ways to slip in -- as is the case in any project where more than one brain is involved. I don't know if you read all the way through this thread (and my mini-essays), but I think some of our speculation is along parallel tracks. To boil down:
I retain the implicit Gold-Red-Blue hierarchy that made it into the final film/trilogy/most of what followed in the EU and Prequels (all the way back to thousands of years before the films). I like that, as it'd conveniently give three squadrons to a Group, as we'd consider it. And twelve ships to a squadron fits three things: We had ships marked all the way up to Red 12, but no higher; a twelve-ship squadron can break down most flexibly, to two-, three-, and four-ship elements; "thirty Rebel ships" is too many for two full-strength squadrons, but works for three partial-strength squadrons (or a combination of full and partial).
Leaving aside terminology, since George used terms interchangeably and the same term for multiple things.
I feel that, while single-type squadrons are our norm out here in Reality-Land, and may have been the preference in the GFFA, the Rebellion tried when it could, but didn't get hung up on it. Leaving out the ship markings, as they'd built one red-marked X-Wing cockpit and one yellow-marked Y-Wing cockpit, we saw a bunch of pilots in clean, blue-marked helmets hopping into both fighter types. I feel like those were the rookies -- or, at least, the less-experienced pilots. That the Rebels were able to throw together a full squadron of somewhat raw pilots to fly high cover and get some combat time in on both craft types, while Gold led and Red covered them.
The call-in may not conform to our standards here, due to technology. If the squadron leaders have a display dedicated to squadron status, as each pilot called in, their ship tally would illuminate green, and the leader could see out of the corner of his eye when everyone had called in, as well as their craft condition during the battle. I feel Red was at nearly full strength -- but only nearly. While two pilots weren't in the call-in, we saw them in the battle (4 and 12), and Reds 7, 9, 10, and 11 called in or had lines. The only one that has neither fighter model nor script callout nor dialogue reference is Red 8, so I presume not present. I feel the call-in is in order of seniority, with Luke being last. Wedge is deputy squadron leader, hence his callsign, but hasn't been in the squadron as long as some. And Luke is filling a blank file -- piloting a ship that was flyable, but had no experienced pilot.
I feel Luke made it into Red on a combination of testing on the simulators, Biggs vouching for him, and Red Leader knowing his dad's piloting skill.
I also feel that the squadron broke down into four-ship elements, with a special proviso for the trench runs -- that being, three ships to make the run with one outside the trench as a spotter. Red Leader assigned Luke to make the run on the port after his because he had the best shot at making the shot, per the testing and Biggs -- and, possibly, because he knew his dad was a Jedi. Wedge and Biggs were assigned as his cover, specifically, ("Keep Reds Two and Three up here and wait for my signal to start your run."). The Y-Wing flying with Luke and Wedge at the end would be their spotter, for which I ended up nominating Red 7, and using the "Red Jammer" Y-Wing model, since the miniature in the film is seen front-on and its markings aren't visible. This, then, would be the Red 2 Y-Wing in ROTJ. He and Wedge got bumped up in the sequence, as the new squadron leader and deputy, while Luke became the new CAG and stayed at Red 5.
As soon as the hit was reported, any other remaining craft would already be on their way out, and from further out than the surface, where those three were (plus the Falcon).
Now, back to the models... As with the rest, I can't wait to see where you go with these, Analyzer. I'm still most impressed with your work on the droids, the pilots' helmets, and all the fiddly **** in the cockpits. Your research has been perfect and your execution brilliant. Would you ever want to re-do these at a larger scale, so you can do the markings and damage and weathering more easily/clearly? Or d'you think you're going to be 592% done with this by the time the squadron's finished? What ships are you still needing? I'd be glad to contribute.